Answers to Key DOCSIS 3.1 Migration Questions

24 Apr 2014

Jeff Walker-Sr. Director, CMTS Product Marketing, ARRIS

With more headlines and data pointing to consumers’ increasing desire for TV Anywhere, multiscreen services, OTT and IP video, we know it’s crucial for service providers to look for ways to further optimize their network.

More providers than ever are transitioning to higher-speed, wideband DOCSIS 3.0 technology. In fact, DOCSIS 3.0 device shipments are expected to comprise nearly 90 percent of worldwide cable CPE shipments in 2014. And the good news is that by taking full advantage of DOCSIS 3.0, service providers not only optimize the performance of their networks, but also prepare those networks for a smooth migration to DOCSIS 3.1.

So where exactly are we in regards to the DOCSIS 3.1 migration? How do cable providers get there? And perhaps the question on most everyone’s mind…is it possible to ensure a smooth migration path? Thankfully, the short answer to the last question is “yes.” But let’s address these questions in greater detail – as well as some additional key points related to DOCSIS 3.1.

First, what exactly will DOCSIS 3.1 do for cable providers? Under appropriate conditions, DOCSIS 3.1 will enable providers to achieve up to a 50 percent increase in data throughput in the same spectrum supporting speeds up to 10 Gbps in the downstream and 1+ Gbps in the upstream.

DOCSIS 3.1 enables expanded speeds through the use of OFDM, which uses multiple sub-carriers in channels up to 192 MHz in width, and Low Density Parity Check (LDPC) forward error correction, which is more efficient than the Reed-Solomon FEC codes used in early DOCSIS versions. The combination of OFDM and LDPC allows providers to use higher modulation orders – 1024, 2048 and 4096 QAM – and enable maximum throughput across various HFC plant conditions.

So where do we stand in the DOCSIS 3.1 migration timeline? DOCSIS 3.1 specifications were released in October 2013, and many vendors are currently developing compatible products. DOCSIS 3.1 enables providers to provide compelling service offerings in a dynamic, competitive marketplace. They can meet the growing demand for managed and OTT IP video services as well as data and traditional video services, such as VOD and nDVR.

The expectation is DOCSIS 3.1 testing will begin later this year and into 2015. Deployments will more than likely begin in late 2015 and early 2016. But it’s crucial for providers making significant investments in their deployed DOCSIS 3.0 CCAP technology to offer software upgrades to key aspects of DOCSIS 3.1. This will enable them to offer enhanced downstream speeds beyond what is possible with the bonding of multiple 6 or 8 MHz channels.

Maybe by now you’re wondering how one might approach this migration path? Thankfully, the migration to DOCSIS 3.1 can be a multi-phased approach making it easier to adapt to the change.

It’s good to know from the start that the migration can be done separately on the downstream and upstream channels. This allows for quicker expansion on the congested downstream channels using some of the DOCSIS 3.1 features. From there, upstream support can be implemented later when additional upstream bandwidth is necessary.

Additionally, providers can start using DOCSIS 3.1 on their existing spectrum in 96MHz or 192MHz blocks and then later adapt their plant and expand to use the higher downstream frequencies up to 1.2 GHz or 1.7 GHz defined in the standards. This approach can make use of “holes” in existing spectrum, and support the gradual insertion of the DOCSIS 3.1 modems into their systems.

One of the operating modes that can aid in the migration to DOCSIS 3.1 is enabled by turning off a block of OFDM sub-carriers in the OFDM channel and operating a single-carrier QAM channel within that spectrum. DOCSIS 3.1 modems and DOCSIS 3.0 modems will be able to operate in the same serving group with the DOCSIS 3.1 modems using both the OFDM and SC-QAM channels and DOCSIS 3.0 modems operating in single-carrier QAM channels.

Finally, the DOCSIS 3.1 migration is made easier and more cost-effective if the same CCAP line cards being used for DOCSIS 3.0 services can be upgraded to support 3.1 via a software upgrade. This saves the provider from an expensive line card replacement. It is also important to have a CCAP with the necessary capacity in the switch fabric, mid-plane, power and cooling. Ultimately, the overall system should scale to beyond 1 Terabit/s of throughput with the appropriate QoS control, traffic managers and network-side interfaces.

In summary, the DOCSIS 3.1 migration aims to be fairly straightforward because of both backward compatibility with DOCSIS 3.0 modems and gateways AND the ability to preserve today’s CCAP investments. Testing of compatible cable modems and gateways will commence later this year followed by upgrades to deployed CCAP systems. All of these initiatives strengthen the cable providers’ position to optimize the performance of their systems to support the growing demand for IP video, data and traditional video services.

We’re not too far away, and I’m looking forward to sharing more updates as we continue down the path to DOCSIS 3.1.